The riser thus is a key element for offshore drilling at great water depths and it therefore has to be studied with great care. The architecture of such a riser depends on a certain number of parameters related to the operating and environmental conditions, such as the water depth, the maximum density of the drilling mud, the diameter of the peripheral lines (kill line, choke line) and their working pressure, the states of the sea and the current profiles, the offset of the (dynamically-positioned or not) floating support. The conditions are different in the drilling mode (riser connected to the wellhead and hanging from the tensioning means) and in the disconnected mode (riser suspended below the floating support, suspended from the drilling table without the agency of the tensioning means).
All these parameters have to be taken into account for dimensioning each component of the riser system: the main pipe, the peripheral lines, the connectors, the floats (buoyancy and distribution), the tensioning system . . . , while observing the standard safety rules and the drilling contractors' usual procedures.